Hubble Space Telescope Near-Ultraviolet Spectroscopy of the Bright CEMP-no Star BD+44 493

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We present an elemental-abundance analysis, in the near-ultraviolet (NUV) spectral range, for the extremely metal-poor star BD+44 493, a 9th magnitude sub-giant with [Fe/H] = -3.8 and enhanced carbon, based on data acquired with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope.

• This star is the brightest example of a class of objects that, unlike the great majority of carbon-enhanced metal-poor (CEMP) stars, does not exhibit over-abundances of heavy neutron-capture elements (CEMP-no).
• In this paper, we validate the abundance determinations for a number of species that were previously studied in the optical region, and obtain strong upper limits for beryllium and boron, as well as for neutron-capture elements from zirconium to platinum, many of which are not accessible from ground-based spectra.
• The boron upper limit we obtain for BD+44 493, logeps(B) < -0.70, the first such measurement for a CEMP star, is the lowest yet found for very and extremely metal-poor stars.